Soybean Yield and Nutrient Composition as Affected by Soil and Foliar Fertilizations

Abstract

Soil fertilizer application and foliar fertilization offer a possible means of increasing soybean [Glycine max (L.) Merr.] yield in Thailand but little is known of appropriate foliar fertilizer use to supplement soil fertilization. Field experiment was conducted twice to determine the effects of soil N P
K fertilization together with foliar fertilizers containing macronutrients and micronutrients on growth, yield and nutrient composition of soybean (Sukhothai 1 and KUSL 20004 cultivars). The treatments were arranged in 3 x 3 factorial experiment in randomized complete block. Three methods of soil fertilization were control (S0), 18 kg N ha^-1 at 7 days after seeding (DAS) (S1), and 18 kg N ha^-1 at 7 DAS + 18 – 18 – 18 kg N – P₂O₅ – K₂O ha^-1 at 30 DAS (S2). Foliar fertilizer contained both macronutrients and micronutrients. The three methods of foliar fertilization were control (F0), 3 applications at 34, 42 and 49 DAS (F1) and 6 applications at 20, 27, 34, 42, 49 and 56 DAS (F2). Throughout the studies, soil and foliar fertilizations did not significantly affect growth, yield and yield components of soybean. The concentration of N P K Fe and Zn in shoot at 68 DAS and N P K and Ca in leaves at 89 DAS were not consistently affected by soil and foliar fertilizations. The remarkable effects of soil fertilizers on the concentrations of Ca Mn and Cu in shoot, and Mg Fe Mn and Cu in leaves were observed. Foliar fertilizations increased Fe and Cu concentrations in leaves. The nutrient concentrations of soybean shoot and leaves under this investigation were in sufficient ranges which were agreeable with soil test results. This finding indicated that the soil can provide sufficient nutrients for soybean growth and yield under this condition. Therefore, soil and foliar fertilization will not be economically feasible.